EP0730172B1 - Add-drop optical multiplexer comprising optical circulators and photoinscripted Bragg-gratings - Google Patents

Add-drop optical multiplexer comprising optical circulators and photoinscripted Bragg-gratings Download PDF

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Publication number
EP0730172B1
EP0730172B1 EP96400394A EP96400394A EP0730172B1 EP 0730172 B1 EP0730172 B1 EP 0730172B1 EP 96400394 A EP96400394 A EP 96400394A EP 96400394 A EP96400394 A EP 96400394A EP 0730172 B1 EP0730172 B1 EP 0730172B1
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European Patent Office
Prior art keywords
optical
wavelength
signals
signal
circulator
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German (de)
French (fr)
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EP0730172A1 (en
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Mouhammad Jamil Chawki
Eric Delevaque
Valérie Tholey
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Orange SA
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France Telecom SA
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
    • G02B6/29316—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide
    • G02B6/29317—Light guides of the optical fibre type
    • G02B6/29319—With a cascade of diffractive elements or of diffraction operations
    • G02B6/2932—With a cascade of diffractive elements or of diffraction operations comprising a directional router, e.g. directional coupler, circulator
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
    • G02B6/29316—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide
    • G02B6/29317—Light guides of the optical fibre type
    • G02B6/29322—Diffractive elements of the tunable type
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
    • G02B6/2938—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
    • G02B6/29382—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM including at least adding or dropping a signal, i.e. passing the majority of signals
    • G02B6/29383—Adding and dropping
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0201—Add-and-drop multiplexing
    • H04J14/0202—Arrangements therefor
    • H04J14/0206—Express channels arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0201—Add-and-drop multiplexing
    • H04J14/0202—Arrangements therefor
    • H04J14/021—Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0201—Add-and-drop multiplexing
    • H04J14/0202—Arrangements therefor
    • H04J14/0213—Groups of channels or wave bands arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/02195—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for tuning the grating
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
    • G02B6/29316—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide
    • G02B6/29325—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide of the slab or planar or plate like form, i.e. confinement in a single transverse dimension only
    • G02B6/29328—Diffractive elements operating in reflection
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
    • G02B6/29316—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide
    • G02B6/29325—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide of the slab or planar or plate like form, i.e. confinement in a single transverse dimension only
    • G02B6/29329—Diffractive elements operating in transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0201—Add-and-drop multiplexing
    • H04J14/0202—Arrangements therefor
    • H04J14/0209—Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers

Definitions

  • the present invention relates to an optical add-drop multiplexer .
  • the MICROWAVE AND OPTICAL TECHNOLOGY document LETTERS, vol. 7, n ° 11, August 1994, pages 499-501, discloses a optical multiplexer intended to extract from a set of signals optics whose wavelengths belong to a set of wavelengths at least one optical signal having a wavelength determined, chosen from said set of wavelengths.
  • This multiplexer includes an optical circulator comprising an input intended to receive the set of signals and an output, and a means of optical selection which is coupled on one side to the circulator and which comprises at least one photo-registered Bragg network, this Bragg network photoinscribed being associated with the determined wavelength and able to stand find in a state where it reflects the signal having this wavelength determined and where it transmits signals having a wavelength different from the latter, the selection means cooperating with the optical circulator for the extraction of said optical signal.
  • the object of the present invention is to remedy this drawback by proposing a insertion-extraction multiplexer which leads to lower optical losses than those of these known multiplexers.
  • the invention even makes it possible to amplify the optical signals that are inserted and those that are extracts and / or have a multiplexer programmable.
  • the multiplexer according to the present invention is defined in the appended independent claims, which are delimited in the form of a preamble and a characterizing part with respect to the document Microware and Optical Technology Letters, vol 7, No. 11 August 1994.
  • the dependent claims define optional features of the invention.
  • optical insertion-extraction multiplexer which is schematically shown in Figure 1, is intended to be inserted into a set of optical signals and to extract signals from this set of signals optics having determined wavelengths.
  • Wavelengths of optical signals considered belong to a set of lengths ⁇ 1 ... ⁇ i ... ⁇ N, where N is an integer greater than 1.
  • the multiplexer shown in Figure 1 is inserted into an optical line LO forming by example an optical loop in which we find other optical multiplexers not shown, identical to that of FIG. 1 and situated upstream and downstream of it on the optical line LO.
  • This line is crossed by the signals wavelengths ⁇ 1 ... ⁇ i ... ⁇ N.
  • this network reflects incident optical signals having the wavelength on which it is set and transmits signals optics not having this wavelength.
  • this network transmits incident optical signals whatever the wavelength of these.
  • Such a network which, as we recall, is written on an optical guide, for example a fiber optic or planar guide (for example in silicon, InP or lithium niobate), works in transmission as a rejector filter and reflection as a bandpass filter.
  • an optical guide for example a fiber optic or planar guide (for example in silicon, InP or lithium niobate)
  • the R1 ... RN networks of the multiplexer of the Figure 1 are programmable.
  • each of them can be set or not to the corresponding wavelength.
  • the control means MC is able to place selectively each of the R1 ... RN networks in the second corresponding state.
  • this MC control means includes means for applying a constraint mechanical (piezoelectric devices) or a thermal heating (Peltier effect devices) at each of the R1 ... RN networks.
  • Each network can thus be adjusted (the piezoelectric or Peltier effect device correspondent is inactive) or not set (this device is activated) on its wavelength associated.
  • an optical circulator is an optical coupling system, which is generally made from optical fibers, which is independent of polarization and that has a low loss insertion, the latter being of the order of 1 dB.
  • This optical coupling system uses the optical isolation technique.
  • each of the optical circulators C1 and C2 has three ports optical, namely the ports p1 and p2 already mentioned and a other port p3.
  • Port p1 of circulator C1 is connected to the LO line located upstream of the multiplexer and corresponds to the E input of the multiplexer.
  • the port p2 of this circulator C1 corresponds at the extraction output X of the multiplexer.
  • Port p1 of circulator C2 corresponds to insertion input I of this multiplexer.
  • the port p2 of this circulator C2 is connected to the LO line located downstream of the multiplexer and corresponds to the output S of the multiplexer.
  • Each of the circulators C1 and C2 includes a first optical isolator i1 and a second i2 optical isolator.
  • the input of the isolator i1 and the output of the isolator i2 are respectively coupled to port p1 and at port p2, as seen in Figure 1.
  • the output of isolator i1 and the input of the i2 isolator are optically coupled to the p3 port.
  • This p3 port is itself optically coupled by means of optical selection MS and, more precisely, to the Bragg network photoregistered R1 with regard to port p3 of C1, as seen in figure 1.
  • this coupling between port p3 and the network R1 is done via an optical amplifying medium bidirectional AO which is for example a medium fiber optic amplifier or medium semiconductor amplifier.
  • Ports p1 and p2 are fully isolated one from the other, the insulation being greater than 30 dB.
  • Port p3 of circulator C2 is optically coupled to the Bragg network photoinscribed RN.
  • the N programmable R1 ... RN networks determine the wavelength (s) to extract on the port p2 of circulator C1 according to the positions of these networks.
  • a signal wavelength ⁇ i is extracted from the signals reaching input E of the optical multiplexer and a signal wavelength ⁇ i is also inserted in these signals.
  • the network Ri is set to this wavelength ⁇ i.
  • the other networks R1 ... Ri-1, Ri + 1 ... RN are, on the contrary, not set on the lengths corresponding to them.
  • the optical amplifier medium AO is placed not between circulator C1 and network R1 but between RN network and circulator C2.
  • the circulators C1 and C2 ensure the isolation of the amplifying medium AO from optical reflections.
  • the amplifying medium (s) optics have stabilized gain.
  • a plurality of networks R1 ... RN are regulated on the corresponding wavelengths while this is not the case for other networks.
  • the multiplexer includes only one Bragg network photoregistered which is set to the corresponding wavelength (and which is therefore in his normal state, without the need for means of ordered).
  • Input E and output S of this multiplexer are on the same circulator optical, namely circulator C1.
  • the insert-extract function is as for it carried out using a second circulator, namely circulator C2.
  • the multiplexer of the Figure 2 is made in the same way as that of the figure 1 except that the setting of the Bragg photoinscribed is different.
  • the input port p1 and the output port p2 of circulator C1 of the multiplexer of figure 2 correspond respectively to the entry E and at the output S of the multiplexer of FIG. 2.
  • the input port p1 and the output port p2 of circulator C2 of this multiplexer of figure 2 correspond respectively to the entry of insertion I and at the extraction output X of the multiplexer of the figure 2.
  • Optical signals including lengths wave belong to the set ⁇ 1 ... ⁇ N but differ from ⁇ i, arrive at input E of the multiplexer then pass through circulator C1 to reach the MS selection means where they are reflected by them corresponding photo-registered networks.
  • An optical signal of wavelength ⁇ i injected at input I crosses all R1 networks ... RN to also reach exit S.
  • the AO bi-directional optical amplifier medium is still inserted between port p3 of circulator C1 and the network R1.
  • any signal to be inserted undergoes a simple amplification from this medium AO amplifier and the same is true for any signal to extract.
  • a multiplexer conforming to the invention which is comparable to that of FIG. 1 but which includes one or a plurality of networks of Bragg photo-subscribers who remain "fixed” (ie in their first state (natural state) and which does not therefore requires no means of control. With this multiplexer we are able to insert and / or extract the wavelength (s) corresponding to this (these) networks.
  • FIG. 3 representing a multiplexer conforming to the invention identical to that of FIG. 1, except for the means of selection which, in the case of the Figure 3, includes only the networks Ri and Ri + 1 which are connected in series and remain constantly in their first state (there is no MC control means).
  • This Figure 3 multiplexer allows you to insert and / or extract signals of wavelengths ⁇ i and ⁇ i + 1.
  • FIG. 4 representing a multiplexer conforming to the invention identical to that of FIG. 2, except for the means of selection which, in the case of the FIG. 4, includes only the networks R1, ..., Ri-1, Ri + 2, ..., RN which are connected in series and remain constantly in their first state (there is no MC control means).
  • This multiplexer of figure 4 allows to insert and / or extract signals from wavelengths ⁇ i and ⁇ i + 1.
  • Figure 5 schematically illustrates a another particular embodiment of the multiplexer object of the invention, comprising an optical circulator C4 to four successive ports p1, p2, p3 and p4 which are separated from each other by three isolators optics i1, i2, i3.
  • the multiplexer of Figure 5 includes also a means of selection MS composed of a first set and a second set of Bragg gratings photoinscribed. These sets are identical and each of them includes the N-1 networks R1, ..., Ri-1, Ri + 1, ..., RN mentioned above, connected in series and remaining in their first state.
  • the network R1 of the first set is connected at port 2 of circulator C4, preferably by through an optical amplifier medium AO.
  • the free end of the RN network of this first set constitutes the extraction output X of the multiplexer.
  • the network R1 of the second set is connected at port p3 of circulator C4, preferably by through an optical amplifier medium AO.
  • the free end of the RN network of this second set constitutes the insertion input of the multiplexer.
  • the port p1 of the circulator corresponds to input E of the multiplexer and receives signals from respective wavelengths ⁇ 1, ..., ⁇ i, ..., ⁇ N.
  • the wavelength signal ⁇ i is extracted at X.
  • the port p4 of the circulator corresponds to the output S of the multiplexer and provides unextracted signals, from wavelengths ⁇ 1, ..., ⁇ i-1, ⁇ i + 1, ..., ⁇ N, and the signal inserted, of wavelength ⁇ i.
  • the optical isolation of these media amplifiers is obtained, on the one hand, by the isolators of circulator C4 and, on the other side, by i4 and i5 optical isolators that are placed respectively at the extraction output X and at the input Insertion I, as seen in Figure 5.
  • the first set can include one or more fixed networks and the second set can understand this or these networks fixed. We can then extract and / or insert the wavelengths not reflected by this or these networks.
  • the use of one or two optical amplifier media provides an optical insertion-extraction multiplexer "with gain "ie where the amplification function is integrated, resulting in less expensive equipment than optical insertion-extraction multiplexer to which would add one or more optical amplifiers.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Communication System (AREA)

Description

DOMAINE TECHNIQUETECHNICAL AREA

La présente invention concerne un multiplexeur optique à insertion-extraction (" optical add-drop multiplexer ").The present invention relates to an optical add-drop multiplexer .

Elle s'applique notamment au domaine des télécommunications optiques.It applies in particular to the field of optical telecommunications.

ETAT DE LA TECHNIQUE ANTERIEURESTATE OF THE PRIOR ART

On connaít diverses architectures de réseaux de télécommunications utilisant des guides optiques et des multiplexeurs optiques à insertion-extraction à base de filtres acousto-optiques ou de filtres de Fabry-Pérot.We know various architectures of telecommunications networks using guides optical and optical insertion-extraction multiplexers based on acousto-optical filters or Fabry-Pérot filters.

Ces multiplexeurs à insertion-extraction connus présentent l'inconvénient de conduire à de fortes pertes optiques tant à l'insertion qu'à l'extraction.These insertion-extraction multiplexers known have the disadvantage of leading to high optical losses both at insertion and extraction.

Le document MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, vol. 7, n° 11, Août 1994, pages 499-501, divulgue un multiplexeur optique destiné à extraire d'un ensemble de signaux optiques dont les longueurs d'onde appartiennent à un ensemble de longueurs d'onde au moins un signal optique ayant une longueur d'onde déterminée, choisie dans ledit ensemble de longueurs d'onde. Ce multiplexeur comprend un circulateur optique comprenant une entrée destinée à recevoir l'ensemble de signaux et une sortie, et un moyen de sélection optique qui est couplé d'un côté au circulateur et qui comprend au moins un réseau de Bragg photoinscrit, ce réseau de Bragg photoinscrit étant associé à la longueur d'onde déterminée et apte à se trouver dans un état où il réfléchit le signal ayant cette longueur d'onde déterminée et où il transmet les signaux ayant une longueur d'onde différente de cette dernière, le moyen de sélection coopérant avec le circulateur optique en vue de l'extraction dudit signal optique.The MICROWAVE AND OPTICAL TECHNOLOGY document LETTERS, vol. 7, n ° 11, August 1994, pages 499-501, discloses a optical multiplexer intended to extract from a set of signals optics whose wavelengths belong to a set of wavelengths at least one optical signal having a wavelength determined, chosen from said set of wavelengths. This multiplexer includes an optical circulator comprising an input intended to receive the set of signals and an output, and a means of optical selection which is coupled on one side to the circulator and which comprises at least one photo-registered Bragg network, this Bragg network photoinscribed being associated with the determined wavelength and able to stand find in a state where it reflects the signal having this wavelength determined and where it transmits signals having a wavelength different from the latter, the selection means cooperating with the optical circulator for the extraction of said optical signal.

EXPOSE DE L'INVENTIONSTATEMENT OF THE INVENTION

La présente invention a pour but de remédier à cet inconvénient en proposant un multiplexeur à insertion-extraction qui conduit à des pertes optiques moins élevées que celles de ces multiplexeurs connus.The object of the present invention is to remedy this drawback by proposing a insertion-extraction multiplexer which leads to lower optical losses than those of these known multiplexers.

Dans certains modes de réalisation particuliers, l'invention permet même d'amplifier les signaux optíques qui sont insérés et ceux qui sont extraits et/ou de disposer d'un multiplexeur programmable.In some embodiments individuals, the invention even makes it possible to amplify the optical signals that are inserted and those that are extracts and / or have a multiplexer programmable.

Le multiplexeur conforme à la présente invention est défini dans les revendications indépendantes annexées, lesquelles sont délimitées sous forme d'un préambule et d'une partie caractérisante par rapport au document Microware and Optical Technology Letters, vol 7, N°11 Aout 1994. Les revendications dépendantes définissent des caractéristiques optionnelles de l'invention. The multiplexer according to the present invention is defined in the appended independent claims, which are delimited in the form of a preamble and a characterizing part with respect to the document Microware and Optical Technology Letters, vol 7, No. 11 August 1994. The dependent claims define optional features of the invention.

BREVE DESCRIPTION DES DESSINSBRIEF DESCRIPTION OF THE DRAWINGS

La présente invention sera mieux comprise à la lecture de la description d'exemples de réalisation donnés ci-après, à titre purement indicatif et nullement limitatif, en faisant référence aux dessins annexés sur lesquels :

  • les figures 1 à 4 sont des vues schématiques de modes de réalisation particuliers du multiplexeur optique à insertion-extraction objet de l'invention, utilisant deux circulateurs optiques à trois ports, et
  • la figure 5 est une vue schématique d'un autre mode de réalisation particulier de ce multiplexeur, utilisant un circulateur optique à quatre ports.
The present invention will be better understood on reading the description of exemplary embodiments given below, by way of purely indicative and in no way limiting, with reference to the appended drawings in which:
  • FIGS. 1 to 4 are schematic views of particular embodiments of the optical insertion-extraction multiplexer object of the invention, using two optical circulators with three ports, and
  • FIG. 5 is a schematic view of another particular embodiment of this multiplexer, using an optical circulator with four ports.

EXPOSE DETAILLE DE MODES DE REALISATION PARTICULIERSDETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

Le multiplexeur optique à insertion-extraction conforme à l'invention, qui est schématiquement représenté sur la figure 1, est destiné à insérer dans un ensemble de signaux optiques et à extraire de cet ensemble de signaux des signaux optiques ayant des longueurs d'onde déterminées.The optical insertion-extraction multiplexer according to the invention, which is schematically shown in Figure 1, is intended to be inserted into a set of optical signals and to extract signals from this set of signals optics having determined wavelengths.

Les longueurs d'onde des signaux optiques considérés appartiennent à un ensemble de longueurs d'onde λ1 ... λi ... λN, où N est un nombre entier supérieur à 1.Wavelengths of optical signals considered belong to a set of lengths λ1 ... λi ... λN, where N is an integer greater than 1.

On cherche par exemple à insérer et/ou extraire un signal dont la longueur d'onde est choisie dans l'ensemble de longueurs d'onde λ1 ... λN et vaut par exemple λi, où 1≤i≤N.We try for example to insert and / or extract a signal whose wavelength is chosen in the set of wavelengths λ1 ... λN and is equal to for example λi, where 1≤i≤N.

Le multiplexeur représenté sur la figure 1 est inséré dans une ligne optique LO formant par exemple une boucle optique dans laquelle on trouve d'autres multiplexeurs optiques non représentés, identiques à celui de la figure 1 et situés en amont et en aval de celui-ci sur la ligne optique LO.The multiplexer shown in Figure 1 is inserted into an optical line LO forming by example an optical loop in which we find other optical multiplexers not shown, identical to that of FIG. 1 and situated upstream and downstream of it on the optical line LO.

Cette ligne est parcourue par les signaux de longueurs d'onde λ1 ... λi ... λN.This line is crossed by the signals wavelengths λ1 ... λi ... λN.

Le multiplexeur optique conforme à l'invention, qui est représenté sur la figure 1, comprend :

  • un premier circulateur optique C1 à trois ports comprenant un port d'entrée p1, qui est destiné à recevoir l'ensemble de signaux, un port intermédiaire p3, et un port de sortie p2,
  • un deuxième circulateur optique C2 à trois ports comprenant un port d'entrée p1, qui est destiné à recevoir le signal à insérer dans l'ensemble de signaux, un port intermédiaire p3, et un port de sortie p2,
  • un moyen de sélection optique MS qui est optiquement couplé, d'un côté, au port intermédiaire p3 du premier circulateur C1 et, de l'autre côté, au port intermédiaire p3 du deuxième circulateur C2 et qui comprend une pluralité de réseaux de Bragg photoinscrits R1 ... Ri .... RN qui sont montés en série et qui sont respectivement associés aux longueurs d'onde λ1 ... λi ... λN, et
  • un moyen MC de commande électrique de ce moyen de sélection MS.
The optical multiplexer according to the invention, which is shown in FIG. 1, comprises:
  • a first three-port optical circulator C1 comprising an input port p1, which is intended to receive the set of signals, an intermediate port p3, and an output port p2,
  • a second three-port optical circulator C2 comprising an input port p1, which is intended to receive the signal to be inserted into the signal assembly, an intermediate port p3, and an output port p2,
  • an optical selection means MS which is optically coupled, on the one hand, to the intermediate port p3 of the first circulator C1 and, on the other hand, to the intermediate port p3 of the second circulator C2 and which comprises a plurality of photo-registered Bragg gratings R1 ... Ri .... RN which are connected in series and which are respectively associated with the wavelengths λ1 ... λi ... λN, and
  • a means MC for electrical control of this selection means MS.

Chacun des réseaux R1 ... Ri ... RN est apte à se trouver :

  • soit dans un premier état, état naturel dans lequel il est "calé", c'est-à-dire réglé, sur la longueur d'onde correspondante,
  • soit dans un deuxième état dans lequel il n'est pas réglé sur cette longueur d'onde.
Each of the networks R1 ... Ri ... RN is capable of being:
  • either in a first state, natural state in which it is "stalled", that is to say adjusted, on the corresponding wavelength,
  • either in a second state in which it is not set to this wavelength.

Dans le premier état, ce réseau réfléchit les signaux optiques incidents ayant la longueur d'onde sur laquelle il est réglé et transmet les signaux optiques n'ayant pas cette longueur d'onde.In the first state, this network reflects incident optical signals having the wavelength on which it is set and transmits signals optics not having this wavelength.

Dans le deuxième état, ce réseau transmet les signaux optiques incidents quelle que soit la longueur d'onde de ceux-ci.In the second state, this network transmits incident optical signals whatever the wavelength of these.

Un tel réseau, qui -on le rappelle- est inscrit sur un guide optique, par exemple une fibre optique ou un guide planaire (par exemple en silicium, en InP ou en niobate de lithium), fonctionne en transmission en tant que filtre réjecteur et en réflexion en tant que filtre passe-bande.Such a network, which, as we recall, is written on an optical guide, for example a fiber optic or planar guide (for example in silicon, InP or lithium niobate), works in transmission as a rejector filter and reflection as a bandpass filter.

Les réseaux R1 ... RN du multiplexeur de la figure 1 sont programmables.The R1 ... RN networks of the multiplexer of the Figure 1 are programmable.

En effet, chacun d'entre eux peut être réglé ou non sur la longueur d'onde qui lui correspond.Indeed, each of them can be set or not to the corresponding wavelength.

On connaít des réseaux de Bragg photoinscrits dont le taux de réjection atteint 99% (20 dB).We know Bragg gratings photo-registrants with a rejection rate of 99% (20 dB).

Le moyen de commande MC est apte à placer sélectivement chacun des réseaux R1 ... RN dans le deuxième état correspondant.The control means MC is able to place selectively each of the R1 ... RN networks in the second corresponding state.

Pour ce faire, ce moyen de commande MC comprend des moyens d'application d'une contrainte mécanique (dispositifs piézoélectriques) ou d'un échauffement thermique (dispositifs à effet Peltier) à chacun des réseaux R1 ... RN.To do this, this MC control means includes means for applying a constraint mechanical (piezoelectric devices) or a thermal heating (Peltier effect devices) at each of the R1 ... RN networks.

L'application d'une telle contrainte mécanique ou d'un tel échauffement thermique sur un réseau de Bragg photoinscrit permet d'obtenir une accordabilité de quelques nanomètres par commande électrique.The application of such a constraint mechanical or such thermal heating on a Bragg network photoinscribed allows to obtain a tunability of a few nanometers per order electric.

Chaque réseau peut ainsi être réglé (le dispositif piézoélectrique ou à effet Peltier correspondant est inactivé) ou non réglé (ce dispositif est activé) sur la longueur d'onde qui lui est associée.Each network can thus be adjusted (the piezoelectric or Peltier effect device correspondent is inactive) or not set (this device is activated) on its wavelength associated.

On considère maintenant les circulateurs optiques C1 et C2.We now consider the circulators C1 and C2 optics.

On rappelle qu'un circulateur optique est un système de couplage optique, qui est généralement fait à partir de fibres optiques, qui est indépendant de la polarisation et qui a une faible perte d'insertion, cette dernière étant de l'ordre de 1 dB.Remember that an optical circulator is an optical coupling system, which is generally made from optical fibers, which is independent of polarization and that has a low loss insertion, the latter being of the order of 1 dB.

Ce système de couplage optique utilise la technique de l'isolation optique.This optical coupling system uses the optical isolation technique.

Dans l'exemple représenté sur la figure 1, chacun des circulateurs optiques C1 et C2 a trois ports optiques, à savoir les ports p1 et p2 déjà cités et un autre port p3.In the example shown in Figure 1, each of the optical circulators C1 and C2 has three ports optical, namely the ports p1 and p2 already mentioned and a other port p3.

Le port p1 du circulateur C1 est raccordé à la ligne LO située en amont du multiplexeur et correspond à l'entree E du multiplexeur.Port p1 of circulator C1 is connected to the LO line located upstream of the multiplexer and corresponds to the E input of the multiplexer.

Le port p2 de ce circulateur C1 correspond à la sortie d'extraction X du multiplexeur.The port p2 of this circulator C1 corresponds at the extraction output X of the multiplexer.

Le port p1 du circulateur C2 correspond à l'entrée d'insertion I de ce multiplexeur.Port p1 of circulator C2 corresponds to insertion input I of this multiplexer.

Le port p2 de ce circulateur C2 est raccordé à la ligne LO située en aval du multiplexeur et correspond à la sortie S du multiplexeur.The port p2 of this circulator C2 is connected to the LO line located downstream of the multiplexer and corresponds to the output S of the multiplexer.

Chacun des circulateurs C1 et C2 comprend un premier isolateur optique i1 et un deuxième isolateur optique i2.Each of the circulators C1 and C2 includes a first optical isolator i1 and a second i2 optical isolator.

L'entrée de l'isolateur i1 et la sortie de l'isolateur i2 sont respectivement couplées au port p1 et au port p2, comme on le voit sur la figure 1.The input of the isolator i1 and the output of the isolator i2 are respectively coupled to port p1 and at port p2, as seen in Figure 1.

La sortie de l'isolateur i1 et l'entrée de l'isolateur i2 sont optiquement couplées au port p3.The output of isolator i1 and the input of the i2 isolator are optically coupled to the p3 port.

Ce port p3 est lui même optiquement couplé au moyen de sélection optique MS et, plus précisément, au réseau de Bragg photoinscrit R1 en ce qui concerne le port p3 de C1, comme on le voit sur la figure 1.This p3 port is itself optically coupled by means of optical selection MS and, more precisely, to the Bragg network photoregistered R1 with regard to port p3 of C1, as seen in figure 1.

Dans l'exemple représenté sur cette figure 1, ce couplage entre le port p3 et le réseau R1 se fait par l'intermédiaire d'un milieu amplificateur optique bidirectionnel AO qui est par exemple un milieu amplificateur à fibre optique ou un milieu amplificateur à semiconducteur.In the example shown in this figure 1, this coupling between port p3 and the network R1 is done via an optical amplifying medium bidirectional AO which is for example a medium fiber optic amplifier or medium semiconductor amplifier.

Un signal optique entrant dans le circulateur C1 par le port p3 de celui-ci est totalement transmis au port p2 de ce circulateur C1.An optical signal entering the circulator C1 through port p3 thereof is totally transmitted to port p2 of this circulator C1.

Les ports p1 et p2 sont entièrement isolés l'un de l'autre, l'isolation étant supérieure à 30 dB.Ports p1 and p2 are fully isolated one from the other, the insulation being greater than 30 dB.

Le port p3 du circulateur C2 est optiquement couplé au réseau de Bragg photoinscrit RN.Port p3 of circulator C2 is optically coupled to the Bragg network photoinscribed RN.

Les N réseaux R1 ... RN programmables déterminent la (ou les) longueur(s) d'onde à extraire sur le port p2 du circulateur C1 suivant les positions fréquentielles de ces réseaux.The N programmable R1 ... RN networks determine the wavelength (s) to extract on the port p2 of circulator C1 according to the positions of these networks.

Dans l'exemple représenté, un signal de longueur d'onde λi est extrait des signaux parvenant à l'entrée E du multiplexeur optique et un signal de longueur d'onde λi est également inséré dans ces signaux.In the example shown, a signal wavelength λi is extracted from the signals reaching input E of the optical multiplexer and a signal wavelength λi is also inserted in these signals.

Pour ce faire, le réseau Ri est réglé sur cette longueur d'onde λi.To do this, the network Ri is set to this wavelength λi.

Les autres réseaux R1 ... Ri-1, Ri+1 ... RN ne sont, au contraire, pas réglés sur les longueurs d'onde qui leur correspondent.The other networks R1 ... Ri-1, Ri + 1 ... RN are, on the contrary, not set on the lengths corresponding to them.

Ainsi, tous les signaux d'entrée dont les longueurs d'onde sont différentes de λi passent de l'entrée E à la sortie S du multiplexeur optique.Thus, all the input signals including wavelengths are different from λi pass from input E to output S of the optical multiplexer.

Un signal de longueur d'onde λi, qui pénètre dans ce multiplexeur, est réfléchi par le réseau photoinscrit Ri pour retourner vers ce circulateur C1 et quitter celui-ci par la sortie d'extraction X où il peut être traité par des moyens appropriés non représentés.A signal of wavelength λi, which enters this multiplexer, is reflected by the network photoinscribed Ri to return to this circulator C1 and leave this one by the exit X extraction where it can be processed by means appropriate not shown.

Un signal de longueur d'onde λi provenant d'une source non représentée et pénètrant dans le multiplexeur par l'entrée d'insertion I de celui-ci parvient au réseau Ri, est réfléchi par celui-ci et sort du multiplexeur par la sortie S de celui-ci.A wavelength signal λi from from a source not shown and entering the multiplexer through the insertion input I thereof reaches the network Ri, is reflected by it and leaves the multiplexer via its output S.

Le milieu amplificateur bidirectionnel AO permet :

  • la simple amplification des signaux optiques qui traversent le multiplexeur de la figure 1 et
  • la double amplification d'un signal qui est extrait de ces signaux, un signal inséré n'étant pas amplifié.
The AO bi-directional amplifier medium allows:
  • the simple amplification of the optical signals which pass through the multiplexer of FIG. 1 and
  • double amplification of a signal which is extracted from these signals, an inserted signal not being amplified.

Dans un mode de réalisation non représenté, le milieu amplificateur optique AO est placé non pas entre le circulateur C1 et le réseau R1 mais entre le réseau RN et le circulateur C2.In an embodiment not shown, the optical amplifier medium AO is placed not between circulator C1 and network R1 but between RN network and circulator C2.

Dans ce cas, ce milieu amplificateur permet :

  • la simple amplification des signaux qui traversent le multiplexeur et
  • la double amplification d'un signal inséré, un signal extrait n'étant pas amplifié.
In this case, this amplifying medium allows:
  • the simple amplification of the signals which cross the multiplexer and
  • double amplification of an inserted signal, an extracted signal not being amplified.

Il est à noter que les circulateurs C1 et C2 assurent l'isolation du milieu amplificateur AO vis-à-vis des réflexions optiques.It should be noted that the circulators C1 and C2 ensure the isolation of the amplifying medium AO from optical reflections.

Ainsi, il n'est pas nécessaire d'ajouter des isolateurs optiques au multiplexeur de la figure 1 pour obtenir cette isolation.So there is no need to add optical isolators to the multiplexer of figure 1 to get this insulation.

Pour augmenter l'amplification optique des signaux, on peut utiliser non pas un mais deux milieux amplificateurs optiques, l'un étant placé entre le circulateur C1 et le réseau R1 et l'autre entre le réseau RN et le circulateur C2.To increase the optical amplification of signals, we can use not one but two media optical amplifiers, one being placed between the circulator C1 and network R1 and the other between RN network and circulator C2.

Pour des raisons de stabilité, il est préférable que le ou les milieux amplificateurs optiques aient un gain stabilisé.For reasons of stability, it is preferable than the amplifying medium (s) optics have stabilized gain.

Dans un mode de réalisation non représenté, une pluralité des réseaux R1 ... RN sont réglés sur les longueurs d'onde correspondantes tandis que ce n'est pas le cas des autres réseaux.In an embodiment not shown, a plurality of networks R1 ... RN are regulated on the corresponding wavelengths while this is not the case for other networks.

On règle par exemple les réseaux R1 et RN sur les longueurs d'ondes correspondantes λ1 et λN et les autres réseaux R2 ... RN-1 ne sont pas réglés sur les longueurs d'onde λ2 ... λN-1.We regulate for example the networks R1 and RN on the corresponding wavelengths λ1 and λN and other R2 ... RN-1 networks are not set to the wavelengths λ2 ... λN-1.

Dans ces conditions, on est capable d'insérer dans les signaux qui arrivent à l'entrée du multiplexeur des signaux de longueurs d'onde respectives λ1 et λN et l'on est également capable d'en extraire de tels signaux de longueurs d'onde respectives λ1 et λN.In these conditions, we are able to insert in the signals arriving at the entrance of the wavelength signal multiplexer respective λ1 and λN and we are also able to extract such wavelength signals λ1 and λN respectively.

Dans un autre mode de réalisation non représenté, le multiplexeur ne comprend qu'un seul réseau de Bragg photoinscrit qui est réglé sur la longueur d'onde correspondante (et qui est donc dans son état normal, sans avoir besoin de moyen de commande).In another embodiment not shown, the multiplexer includes only one Bragg network photoregistered which is set to the corresponding wavelength (and which is therefore in his normal state, without the need for means of ordered).

Dans ce cas, on est capable d'insérer dans des signaux incidents et/ou d'extraire de ces signaux incidents un signal ayant cette longueur d'onde.In this case, we are able to insert into incident signals and / or extract from these signals incidents a signal having this wavelength.

On considère maintenant le multiplexeur conforme à l'invention qui est schématiquement représenté sur la figure 2.We now consider the multiplexer according to the invention which is schematically shown in figure 2.

L'entrée E et la sortie S de ce multiplexeur se trouvent sur un même circulateur optique, à savoir le circulateur C1. Input E and output S of this multiplexer are on the same circulator optical, namely circulator C1.

On voit encore sur la figure 2 les deux parties de la ligne optique LO auxquelles sont respectivement reliées l'entrée E et la sortie S du multiplexeur.We can still see in Figure 2 the two parts of the optical line LO to which are respectively connected input E and output S of multiplexer.

La fonction d'insertion-extraction est quant à elle réalisée à l'aide d'un deuxième circulateur, à savoir le circulateur C2.The insert-extract function is as for it carried out using a second circulator, namely circulator C2.

Plus précisément, le multiplexeur de la figure 2 est constitué de la même façon que celui de la figure 1 à ceci près que le réglage des réseaux de Bragg photoinscrits est différent.More specifically, the multiplexer of the Figure 2 is made in the same way as that of the figure 1 except that the setting of the Bragg photoinscribed is different.

Dans l'exemple choisi, où l'on veut insérer un signal de longueur d'onde λi dans les signaux incidents et/ou extraire de ceux-ci un signal ayant également la longueur d'onde λi, tous les réseaux faisant partie des moyens de sélection MS du multiplexeur de la figure 2 sont réglés sur les longueurs d'onde correspondantes à l'exception du réseau photoinscrit Ri correspondant à la longueur d'onde λi qui n'est pas réglé sur cette longueur d'onde λi.In the example chosen, where we want to insert a signal of wavelength λi in the signals incidents and / or extract from them a signal having also the wavelength λi, all networks being part of the selection means MS of the Figure 2 multiplexer are set to corresponding wavelengths except for the photo-registered network Ri corresponding to the length wave λi which is not set to this wavelength .lambda.i.

Dans ces conditions, le port d'entrée p1 et le port de sortie p2 du circulateur C1 du multiplexeur de la figure 2 correspondent respectivement à l'entrée E et à la sortie S du multiplexeur de la figure 2.Under these conditions, the input port p1 and the output port p2 of circulator C1 of the multiplexer of figure 2 correspond respectively to the entry E and at the output S of the multiplexer of FIG. 2.

Le port d'entrée p1 et le port de sortie p2 du circulateur C2 de ce multiplexeur de la figure 2 correspondent respectivement à l'entrée d'insertion I et à la sortie d'extraction X du multiplexeur de la figure 2.The input port p1 and the output port p2 of circulator C2 of this multiplexer of figure 2 correspond respectively to the entry of insertion I and at the extraction output X of the multiplexer of the figure 2.

Les signaux optiques, dont les longueurs d'onde appartiennent à l'ensemble λ1 ... λN mais diffèrent de λi, arrivent à l'entrée E du multiplexeur puis passent dans le circulateur C1 pour arriver au moyen de sélection MS où ils sont réfléchis par les réseaux photoinscrits correspondants.Optical signals, including lengths wave belong to the set λ1 ... λN but differ from λi, arrive at input E of the multiplexer then pass through circulator C1 to reach the MS selection means where they are reflected by them corresponding photo-registered networks.

Ces signaux parviennent alors à la sortie S du multiplexeur en repassant par le circulateur C1.These signals then reach output S of the multiplexer by going back through circulator C1.

Un signal optique de longueur d'onde λi injecté à l'entrée I traverse tous les réseaux R1 ... RN pour parvenir également à la sortie S.An optical signal of wavelength λi injected at input I crosses all R1 networks ... RN to also reach exit S.

Un signal optique de longueur d'onde λi parvenant par l'entrée E du multiplexeur de la figure 2 traverse l'ensemble des réseaux de celui-ci, passe dans le circulateur C2 puis parvient à la sortie d'extraction X.An optical signal of wavelength λi arriving by the input E of the multiplexer of figure 2 crosses all of its networks, goes into circulator C2 then arrives at the exit X.

Au lieu qu'un seul réseau ne soit pas réglé sur la longueur d'onde correspondante, on pourrait ne pas régler une pluralité de réseaux sur les longueurs d'onde correspondantes pour pouvoir insérer et/ou extraire des signaux optiques ayant ces longueurs d'onde.Instead of one network not being tuned on the corresponding wavelength, we could not not set a plurality of networks over the lengths corresponding waveform to be able to insert and / or extract optical signals having these lengths wave.

Dans l'exemple représenté sur la figure 2, le milieu amplificateur optique bidirectionnel AO est encore inséré entre le port p3 du circulateur C1 et le réseau R1.In the example shown in Figure 2, the AO bi-directional optical amplifier medium is still inserted between port p3 of circulator C1 and the network R1.

Dans ces conditions, les signaux qui ne correspondent pas à une longueur d'onde d'extraction et qui parviennent à l'entrée E se retrouvent à la sortie S après avoir été doublement amplifiés par ce milieu amplificateur AO.Under these conditions, the signals which not correspond to an extraction wavelength and who reach the entrance E find themselves at the exit S after having been doubly amplified by this medium AO amplifier.

De plus, tout signal à insérer subit une simple amplification de la part de ce milieu amplificateur AO et il en est de même pour tout signal à extraire.In addition, any signal to be inserted undergoes a simple amplification from this medium AO amplifier and the same is true for any signal to extract.

On pourrait bien entendu placer un autre milieu amplificateur optique bidirectionnel entre le réseau RN et le circulateur C2 du multiplexeur de la figure 2. We could of course place another bi-directional optical amplifier medium between the RN network and circulator C2 of the multiplexer of the figure 2.

On pourrait également utiliser un seul milieu amplificateur optique que l'on placerait entre ce réseau RN et ce circulateur C2.We could also use just one optical amplifier medium that we would place between this RN network and this circulator C2.

Dans ce cas, seuls seraient amplifiés les signaux à extraire et les signaux à insérer.In this case, only the signals to extract and signals to insert.

On peut réaliser un multiplexeur conforme à l'invention, qui est comparable à celui de la figure 1 mais qui comprend un ou une pluralité de réseaux de Bragg photoinscrits qui restent "fixes" (c'est-à-dire dans leur premier état (état naturel) et qui ne nécessite donc aucun moyen de commande. Avec ce multiplexeur on est capable d'insérer et/ou d'extraire la ou les longueurs d'onde correspondant à ce ou ces réseaux.A multiplexer conforming to the invention, which is comparable to that of FIG. 1 but which includes one or a plurality of networks of Bragg photo-subscribers who remain "fixed" (ie in their first state (natural state) and which does not therefore requires no means of control. With this multiplexer we are able to insert and / or extract the wavelength (s) corresponding to this (these) networks.

Ceci est schématiquement illustré par la figure 3 représentant un multiplexeur conforme à l'invention identique à celui de la figure 1, excepté pour le moyen de sélection qui, dans le cas de la figure 3, ne comprend que les réseaux Ri et Ri+1 qui sont montés en série et restent constamment dans leur premier état (il n'y a pas de moyen de commande MC). Ce multiplexeur de la figure 3 permet d'insérer et/ou d'extraire des signaux de longueurs d'onde λi et λi+1.This is schematically illustrated by the FIG. 3 representing a multiplexer conforming to the invention identical to that of FIG. 1, except for the means of selection which, in the case of the Figure 3, includes only the networks Ri and Ri + 1 which are connected in series and remain constantly in their first state (there is no MC control means). This Figure 3 multiplexer allows you to insert and / or extract signals of wavelengths λi and λi + 1.

On peut aussi réaliser un multiplexeur conforme à l'invention, qui est comparable à celui de la figure 2 mais qui comprend un ou une pluralité de réseaux de Bragg photoinscrits qui restent "fixes" (c'est-à-dire dans leur premier état (état naturel) et qui ne nécessite donc aucun moyen de commande. Avec ce multiplexeur on est capable d'insérer et/ou d'extraire les longueurs d'onde restantes non réfléchies par le ou les réseaux.We can also make a multiplexer according to the invention, which is comparable to that of Figure 2 but which includes one or a plurality of photo-registered Bragg gratings that remain "fixed" (i.e. in their first state (natural state) and which therefore requires no means of control. With this multiplexer we are able to insert and / or extract the remaining wavelengths not reflected by the or networks.

Ceci est schématiquement illustré par la figure 4 représentant un multiplexeur conforme à l'invention identique à celui de la figure 2, excepté pour le moyen de sélection qui, dans le cas de la figure 4, ne comprend que les réseaux R1, ..., Ri-1, Ri+2, ..., RN qui sont montés en série et restent constamment dans leur premier état (il n'y a pas de moyen de commande MC). Ce multiplexeur de la figure 4 permet d'insérer et/ou d'extraire des signaux de longueurs d'onde λi et λi+1.This is schematically illustrated by the FIG. 4 representing a multiplexer conforming to the invention identical to that of FIG. 2, except for the means of selection which, in the case of the FIG. 4, includes only the networks R1, ..., Ri-1, Ri + 2, ..., RN which are connected in series and remain constantly in their first state (there is no MC control means). This multiplexer of figure 4 allows to insert and / or extract signals from wavelengths λi and λi + 1.

La figure 5 illustre schématiquement un autre mode de réalisation particulier du multiplexeur objet de l'invention, comprenant un circulateur optique C4 à quatre ports successifs p1, p2, p3 et p4 qui sont séparés les uns des autres par trois isolateurs optiques i1, i2, i3.Figure 5 schematically illustrates a another particular embodiment of the multiplexer object of the invention, comprising an optical circulator C4 to four successive ports p1, p2, p3 and p4 which are separated from each other by three isolators optics i1, i2, i3.

Le multiplexeur de la figure 5 comprend aussi un moyen de sélection MS composé d'un premier ensemble et d'un deuxième ensemble de réseaux de Bragg photoinscrits. Ces ensembles sont identiques et chacun d'eux comprend les N-1 réseaux R1, ..., Ri-1, Ri+1, ..., RN mentionnés plus haut, montés en série et restant dans leur premier état.The multiplexer of Figure 5 includes also a means of selection MS composed of a first set and a second set of Bragg gratings photoinscribed. These sets are identical and each of them includes the N-1 networks R1, ..., Ri-1, Ri + 1, ..., RN mentioned above, connected in series and remaining in their first state.

Le réseau R1 du premier ensemble est relié au port 2 du circulateur C4, de préférence par l'intermédiaire d'un milieu amplificateur optique AO. L'extrémité libre du réseau RN de ce premier ensemble constitue la sortie d'extraction X du multiplexeur.The network R1 of the first set is connected at port 2 of circulator C4, preferably by through an optical amplifier medium AO. The free end of the RN network of this first set constitutes the extraction output X of the multiplexer.

Le réseau R1 du deuxième ensemble est relié au port p3 du circulateur C4, de préférence par l'intermédiaire d'un milieu amplificateur optique AO. L'extrémité libre du réseau RN de ce deuxième ensemble constitue l'entrée d'insertion du multiplexeur.The network R1 of the second set is connected at port p3 of circulator C4, preferably by through an optical amplifier medium AO. The free end of the RN network of this second set constitutes the insertion input of the multiplexer.

Le port p1 du circulateur correspond à l'entrée E du multiplexeur et reçoit des signaux de longueurs d'onde respectives λ1, ..., λi, ..., λN. Le signal de longueur d'onde λi est extrait en X. En I on peut insérer un signal de longueur d'onde λi. Le port p4 du circulateur correspond à la sortie S du multiplexeur et fournit les signaux non extraits,de longueurs d'onde λ1, ..., λi-1, λi+1, ..., λN, et le signal inséré, de longueur d'onde λi.The port p1 of the circulator corresponds to input E of the multiplexer and receives signals from respective wavelengths λ1, ..., λi, ..., λN. The wavelength signal λi is extracted at X. At I we can insert a signal of wavelength λi. The port p4 of the circulator corresponds to the output S of the multiplexer and provides unextracted signals, from wavelengths λ1, ..., λi-1, λi + 1, ..., λN, and the signal inserted, of wavelength λi.

Dans le cas où les milieux amplificateurs AO sont utilisés, l'isolation optique de ces milieux amplificateurs est obtenue, d'un côté, par les isolateurs du circulateur C4 et, de l'autre côté, par des isolateurs optiques i4 et i5 que l'on place respectivement à la sortie d'extraction X et à l'entrée d'insertion I, comme on le voit sur la figure 5.In the case where the amplifying media AO are used, the optical isolation of these media amplifiers is obtained, on the one hand, by the isolators of circulator C4 and, on the other side, by i4 and i5 optical isolators that are placed respectively at the extraction output X and at the input Insertion I, as seen in Figure 5.

Plus généralement, le premier ensemble peut comprendre un ou une pluralité de réseaux fixes et le deuxième ensemble peut comprendre ce ou ces réseaux fixes. On peut alors extraire et/ou insérer les longueurs d'onde non réfléchies par ce ou ces réseaux.More generally, the first set can include one or more fixed networks and the second set can understand this or these networks fixed. We can then extract and / or insert the wavelengths not reflected by this or these networks.

Bien entendu, dans un multiplexeur du genre de celui de la figure 5, on pourrait associer aux réseaux un moyen de commande du genre du moyen MC mentionné plus haut pour mettre sélectivement ces réseaux dans leur deuxième état.Of course, in a multiplexer like from that of Figure 5, we could associate with networks a means of control of the kind of means MC mentioned above to selectively put these networks in their second state.

Dans l'invention, l'utilisation d'un ou deux milieux amplificateurs optiques permet d'obtenir un multiplexeur optique à insertion-extraction "avec gain" c'est-à-dire où la fonction d'amplification est intégrée, d'où un équipement moins coûteux qu'un multiplexeur optique à insertion-extraction auquel on ajouterait un ou des amplificateurs optiques.In the invention, the use of one or two optical amplifier media provides an optical insertion-extraction multiplexer "with gain "ie where the amplification function is integrated, resulting in less expensive equipment than optical insertion-extraction multiplexer to which would add one or more optical amplifiers.

Claims (26)

  1. An optical multiplexer having a drop function so that it is able to drop, from a set of N optical signals whose respective wavelengths belong to a set of N wavelengths (λ1, ..., λi, ... λN), an optical signal having a predetermined wavelength (λi) selected from said set of N wavelengths, said multiplexer comprising:
    at least one optical circulator (C1) having three ports (p1, p3, p2) and adapted so that signals incoming at any of its ports exit via the immediately following port, its first port (p1) constituting an input adapted to receive said set of N signals and its third port (p2) constituting an output, and
    wavelength-selective reflector means (MS) coupled via one end to the second port (p3) of the circulator, comprising at least one photo-induced Bragg grating (Ri; Ri, Ri+1; R1, ..., Ri-1, Ri+2, ..., RN, R1, .... Ri, ..., RN), said wavelength-selective reflector means being adapted to reflect signals from one of two groups of signals, of which a first group comprises the signal having said predetermined wavelength (λi) and the second group comprises the signals having a different wavelength, and being adapted to pass the signals of the other of the two groups, and said wavelength-selective reflector means (MS) co-operating with said optical circulator (C1) to drop said optical signal having said predetermined wavelength (λi),
    which multiplexer is characterized in that it also has an add function so that it is also able to add at least one optical signal at a predetermined wavelength (λi) to said set of optical signals from which said signal at a predetermined wavelength (λi) is dropped,
    the multiplexer further comprising for this purpose a second optical circulator (C2) having three ports (p1, p3, p2), adapted so that signals incoming at any of its ports exit via the immediately following port, said second optical circulator being coupled by its second port (p3) to the other end of said wavelength-selective reflector means (MS), its first port (p1) constituting an input adapted to receive said signal at said predetermined wavelength (λi) to be added to the set of signals and its third port (p2) constituting an output,
    said wavelength-selective reflector means (MS) being adapted for co-operating with the two circulators (C1, C2) so that the outputs (p2) of said two circulators respectively supply said signal (λi) dropped from said set of signals and said set of signals which said signal at said predetermined wavelength (λi) is dropped from and added to.
  2. A multiplexer according to claim 1, characterized in that said wavelength-selective reflector means (MS) are adapted to reflect said predetermined wavelength (λi) of said at least one signal to be dropped and of said at least one signal to be added and to pass the other signals having different wavelengths, the output (p2) of the first circulator (C1) is adapted to supply said signal at said predetermined wavelength (λi) dropped from said set of signals, and the output (p2) of the second circulator (C2) is adapted to supply the set of signals which said signal at said predetermined wavelength (λi) is dropped from and added to.
  3. An optical multiplexer according to claim 2, characterized in that said at least one photo-induced Bragg grating (Ri; Ri, Ri + 1) constituting said wavelength-selective reflector means (MS) is in a natural state in which it reflects said predetermined wavelength (λi).
  4. An optical multiplexer according to claim 3, adapted to drop and to add a single optical signal at a predetermined wavelength (λi), characterized in that said wavelength-selective reflector means (MS) comprise a single photo-induced Bragg grating (Ri) which is in said natural state in which it reflects said predetermined wavelength (λi).
  5. An optical multiplexer according to claim 3, adapted to drop and to add a plurality p of optical signals having respective predetermined wavelengths (λi, λi+1), characterized in that said wavelength-selective reflector means (MS) comprise a corresponding number p of photo-induced Bragg gratings (Ri, Ri+1) in series and all in said natural state in which each reflects one of said predetermined wavelengths (λi, λi+1).
  6. An optical multiplexer according to claim 2, characterized in that:
    said wavelength-selective reflector means (MS) comprise N photo-induced Bragg gratings (R1, ..., Ri, ..., RN) in series and respectively associated with the wavelengths of said set of N wavelengths and each of said gratings is adapted to be either in a natural state in which it reflects the respective wavelength with which it is associated or a second state in which it passes said respective wavelength, and
    said selective reflector means (MS) further comprise control means (MC) adapted to switch each of said gratings selectively to said second state.
  7. An optical multiplexer according to claim 6, adapted to drop and to add a single optical signal having a predetermined wavelength (λi), characterized in that said Bragg grating associated with said predetermined wavelength (λi) is maintained in its first state and each of the other (N-1) gratings is placed in its second state.
  8. An optical multiplexer according to claim 6, adapted to drop and to add a plurality p of optical signals at respective predetermined wavelengths (λi, λi+1), characterized in that the p Bragg gratings associated with said predetermined wavelengths (λi, λi+1) are maintained in their first state and each of the (N-p) other gratings is placed in its second state.
  9. A multiplexer according to claim 1, characterized in that said wavelength-selective reflector means (MS) are adapted to reflect wavelengths other than said predetermined wavelength (λi) of said at least one signal to be dropped and of said at least one signal to be added and to pass said predetermined wavelength (λi) to be dropped and to be added, the output (p2) of the first circulator (C1) is adapted to supply all of the signals which said signal of predetermined wavelength (λi) has been dropped from and added to, and the output (p2) of the second circulator (C2) is adapted to supply said signal at said predetermined wavelength (λi) dropped from said set of signals.
  10. An optical multiplexer according to claim 9, characterized in that said wavelength-selective reflector means (MS) comprise a plurality of photo-induced Bragg gratings (R1, ..., Ri-1, Ri+2, ..., RN) that are associated with respective different wavelengths of the set of wavelengths other than said at least one predetermined wavelength (λi) and are all in a natural state in which they reflect a respective one of said other wavelengths.
  11. An optical multiplexer according to claim 10, adapted to drop and to add a single optical signal at a predetermined wavelength (λi), characterized in that said wavelength-selective reflector means (MS) comprise N-1 photo-induced Bragg gratings.
  12. An optical multiplexer according to claim 10, adapted to drop and to add a plurality p of optical signals at predetermined wavelengths (λi, λi+1), characterized in that said wavelength-selective reflector means (MS) comprise N-p photo-induced Bragg gratings.
  13. An optical multiplexer according to claim 9, characterized in that:
    said wavelength-selective reflector means (MS) comprise N photo-induced Bragg gratings (R1, ..., Ri, RN) in series and associated with respective different wavelengths of said set of N wavelengths and each of said gratings is adapted to be either in a natural state in which it reflects the respective wavelength with which it is associated or in a second state in which it passes said respective wavelength, and
    said selective reflection means (MS) further comprise control means (MC) adapted to switch each of said gratings selectively to said second state.
  14. An optical multiplexer according to claim 13, adapted to drop and to add a single optical signal at a predetermined wavelength (λi), characterized in that whichever of said N Bragg gratings is associated with said predetermined wavelength (λi) is placed in its second state and each of the other N-1 gratings is maintained in its first state.
  15. An optical multiplexer according to claim 13, adapted to drop and to add a plurality p of optical signals at predetermined wavelengths (λi, λi+1), characterized in that said (p) Bragg gratings that are associated with said predetermined wavelengths (λi, λi+1) are placed in their second state and each of the N-p other gratings is maintained in its first state.
  16. A multiplexer according to any one of claims 1 to 15, characterized in that it further comprises at least one optical amplifier medium (AO), said optical amplifier medium being placed between the optical selector means (MS) and either the first or the second circulator (C1, C2).
  17. A multiplexer according to any one of claims 1 to 15, characterized in that it further comprises at least one optical amplifier medium (AO), said optical amplifier medium being placed between the optical selector means (MS) and the first circulator (C1).
  18. A multiplexer according to any one of claims 1 to 17, characterized in that it comprises two optical amplifier media between the optical selector means (MS) and the first and second circulators (C1, C2), respectively.
  19. A multiplexer according to any one of claims 1 to 18, characterized in that each of the first and second optical circulators (C1, C2) comprises a first optical isolator and a second optical isolator, the input of the first isolator and the output of the second isolator are respectively coupled to the input (p1) and to the output (p2) of the corresponding circulator, and the output of the first isolator and the input of the second isolator are coupled to the optical selector means (MS).
  20. An optical multiplexer having a drop function so that it is able to drop, from a set of N optical signals whose respective wavelengths belong to a set of N wavelengths (λ1, ..., λi, ... λN), an optical signal having a predetermined wavelength (λi) selected from said set of N wavelengths, said multiplexer comprising:
    an optical circulator (C4) having at least three ports (p1, p2, p3, p4) and adapted so that signals incoming at any of its ports exit via the immediately following port, its first port (p1) constituting an input adapted to receive said set of N signals and its last port (p4) constituting an output, and
    wavelength-selective reflector means (MS) coupled via a first end to at least one intermediate port (p3) of the circulator, comprising at least one photo-induced Bragg grating (R1, ..., Ri-1, Ri+1 ..., RN), said wavelength-selective reflector means being adapted to reflect one of two groups of signals respectively comprising the signal having said predetermined wavelength (λi) and the signals having a different wavelength and to pass signals of the other group, said wavelength-selective reflector means (MS) co-operating with said optical circulator (C4) to drop said optical signal having said predetermined wavelength (λi),
    which multiplexer is characterized in that it also has an add function so that it is able to add at least one optical signal having a predetermined wavelength (λi) to said set of optical signals from which said signal at said predetermined wavelength (λi) is dropped,
    and in that, to this end:
    the optical circulator (C4) is a four-port circulator, and
    the wavelength-selective reflector means (MS) are coupled to two intermediate ports (p2, p3) of the circulator and respectively comprise a first set of M photo-induced Bragg gratings (R1, .... Ri-1, Ri+1 ..., RN) that are in series and each adapted to reflect a respective wavelength different from said predetermined wavelength (λi), with said first set of gratings coupled at one end to the second port (p2) of the circulator so that its other end constitutes an output adapted to supply said dropped signal having a predetermined wavelength (λi), and a second set of (M) photo-induced Bragg gratings identical to the first set and coupled at one end to the third port (p3) of the circulator, the other end of the second set constituting an input into which is injected the signal having a predetermined wavelength (λi) to be added, with the output (p4) of the circulator adapted to supply said set of signals which the signal at the predetermined wavelength (λi) is dropped from and added to.
  21. An optical multiplexer according to claim 20, characterized in that each Bragg grating of said selector means (MS) is adapted to be in a natural state in which it reflects a respective wavelength different from said predetermined wavelength to be dropped and to be added.
  22. An optical multiplexer according to claim 20, characterized in that each Bragg grating of said selector means (MS) is adapted to be either in a natural state in which it reflects a respective wavelength different from said predetermined wavelength to be dropped and to be added or in a second state in which it passes said respective wavelength and in that the multiplexer further comprises control means adapted to switch each of said gratings selectively to said second state.
  23. An optical multiplexer according to any one of claims 20 to 22 adapted to drop and to add a single optical signal at a predetermined wavelength (λi) and characterized in that M = N - 1.
  24. An optical multiplexer according to any one of claims 20 to 22, adapted to drop and to add a plurality p of optical signals having respective predetermined wavelengths (λi, λi+1), characterized in that M = N-p.
  25. An multiplexer according to any one of claims 20 to 24, characterized in that it further comprises at least one optical amplifier medium (AO) in series with the first and/or second set(s).
  26. A multiplexer according to claim 25, characterized in that each of the first and second sets is in series with at least one optical amplifier medium (AO).
EP96400394A 1995-02-28 1996-02-26 Add-drop optical multiplexer comprising optical circulators and photoinscripted Bragg-gratings Expired - Lifetime EP0730172B1 (en)

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FR9502303A FR2731082B1 (en) 1995-02-28 1995-02-28 OPTICAL INSERTION-EXTRACTION MULTIPLEXER USING OPTICAL CIRCULATORS AND PHOTO-WRITTEN BRAGG ARRAYS

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FR2731082B1 (en) 1997-04-04
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DE69629741D1 (en) 2003-10-09
EP0730172A1 (en) 1996-09-04

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